This invention relates to a method and apparatus for automatically detecting orientation with respect to a predetermined reference, particularly for aligning vehicle headlamps, and more specifically relates to a method and apparatus for automatically detecting the orientation of vehicle headlamps in a predetermined frame of reference and for automatically adjusting the headlamps to obtain a desired orientation thereof.
A wide variety of orientation sensing systems and adjusting means have been employed for the alignment of vehicle headlamps and wheels, surveyors' transits and numerous other machines and devices which require accurate alignment relative to a predetermined reference for proper operation. For example, a number of different types of tools have been employed to align vehicle headlamps in order to properly aim the light beams relative to the true horizontal and relative to the longitudinal axis of the vehicle. The importance of this aiming procedure can be readily appreciated when the problems of visibility and glare are considered.
It can be appreciated that a headlamp which is badly misaligned with respect to the true horizontal may point upwardly or downwardly resulting in poor visibility and hazardous or at least annoying glare to drivers of approaching vehicles. Likewise, a headlamp which is badly misaligned relative to the longitudinal axis of the vehicle may point to the left or right of the path of the vehicle again resulting in poor visibility and possible hazardous conditions for approaching vehicles.
The problem of aligning vehicle headlamps has been approached in a number of ways. One method of aiming headlamps requires the alignment of the vehicle relative to a target and the energization of the headlamps for illumination of the target. Another system for aiming headlamps utilizes an aiming tool which is positioned in abutment with aiming pads defining a reference surface on the headlamp. The headlamps are then aligned by determining the orientation of the tool (and, thus the reference surface) relative to the true horizontal and relative to the longitudinal axis of the vehicle.
One such system of this latter type is disclosed in U.S. Pat. No. 2,997,914, to Hopkins assigned to the assignee of the present invention. The headlamp aiming apparatus of the Hopkins patent is highly advantageous since highly accurate alignment is obtained without, for example, the need for elaborate vehicle positioning stalls and the like.
While highly satisfactory results are obtained through the use of the headlamp aiming apparatus disclosed in Hopkins patent, it would be particularly desirable to provide for the more rapid alignment of vehicle headlamps while simultaneously minimizing the possibility of operator error. For example, where vehicles are mass produced at assembly line speeds, it is useful to be able to accurately aim the vehicle headlamps at speeds consistant with these same assembly line speeds. Moreover, where state codes require periodic vehicle inspections, the rapid and accurate testing of vehicle headlamp alignment, and the subsequent realignment of the headlamps if necessary, is highly desirable.
In addition to the alignment of vehicle headlamps, speed and a high degree of accuracy with minimal chance of operator error may be desirable in detecting and adjusting the orientation of other devices relative to predetermined references. For example, the alignment of a surveyor's transit relative to the true horizontal is extremely important if accurate measurements are to be obtained. Moreover, the alignment of the wheels of a vehicle is highly desirable from the standpoint of maximum tire life and safe vehicle operation at relatively high speeds.
It is accordingly an object of the present invention to provide a novel method an apparatus for automatically detecting the orientation of a member relative to a predetermined reference, particularly with respect to the true horizontal.
It is another object of the present invention to provide a method and apparatus for automatically detecting the orientation of a member relative to a predetermined reference and automatically adjusting the orientation of the member in response to the detected orientation.
It is still another object of the present invention to provide a novel method and apparatus for aiming vehicle headlamps.
It is a further object of the present invention to provide a novel method and apparatus for minimizing the possibility of operator error in the aiming of vehicle headlamps.
It is yet another object of the present invention to provide a novel method and apparatus for automatically detecting headlamp aiming errors and for automatically adjusting the headlamps to compensate for the detected errors.
It is still a further object of the present invention to provide a novel method and apparatus for detecting the orientation of a vehicle headlamp relative to the true horizontal and relative to the longitudinal axis of the vehicle and for automatically adjusting the position of the headlamp in response to a selected one of the detected orientations, the selection being accomplished in response to the position of an adjusting tool used to effect the adjustment.
A preferred embodiment of the invention intended to accomplish at least some of the foregoing objects comprises an aiming tool adapted to be retained in engagement with a reference surface on the vehicle headlamp so that the aiming tool is disposed at a predetermined orientation relative to the reference surface and means carried by the aiming tool for detecting the orientation of the tool relative to the true horizontal and the longitudinal axis of the vehicle. A headlamp adjusting means is provided for modifying the position of the vehicle headlamp in response to the detected orientation of the aiming tool to align the headlamp in a desired orientation relative to the true horizontal and the longitudinal axis of the vehicle.
The adjusting means also includes position responsive switch means for selecting the proper orientation detecting means to effect the headlamp adjustment according to the position of the adjusting means. More specifically, a position responsive switch such as a mercury switch carried by the headlamp adjusting means indicates by its position the direction (up/down, right/left) in which the headlamp will be adjusted in response to the application of a control signal thereto. The position responsive switch, through closure of the proper set of electrical contacts, thereby selects the proper orientation detector for control of the adjusting means.
Another independent aspect of the present invention involves a detecting means including light emitting diodes and photocells, approximately matched as to the wavelengths at which peak emmissivity and spectral response is obtained, used in conjuction with a level means of the type containing two media having different light modifying properties, e.g. a liquid and a gas bubble, to automatically detect the orientation of a member relative to the true horizontal. The level means is desirably constructed so that the bubble position is relatively insensitive to pivotal movement of the level means relative to the true horizontal. The approximate match of the light emitting diodes and photocells results in extremely high sensitivity of the detecting means, thereby compensating for the relative insensitivity of the level means and providing a highly sensitive, very stable automatic orientation detector, the output signal from which may be utilized to indicate, record and/or modify the orientation of the member relative to the true horizontal.
Yet another independent aspect of the present invention involves a detecting means including first and second light detecting means and a light source mounted independently of the detecting means. A wall means defining first and second brightness zones is disposed intermediate the light source and the two light detecting means. The two light detecting means are positioned in the respective brightness zones. The light source illuminates the brightness zones with a light beam originating as a concentrated spot of light and diverging outwardly along the length of the beam.
Other objects and advantages of the present invention will become apparent to one skilled in the art to which the invention pertains from a perusal of the following detailed description of a preferred embodiment of the invention when read in conjunction with the accompanying drawings in which :